Дисертації з теми "In situ micropillar compression"
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Jonsson, Åsa, and Grim Skarsgård. "Synchrotron tomography of pressboard during in-situ compression loading : Construction of compression rig, image acquisition procedure and methods for image processing." Thesis, Uppsala universitet, Tillämpad mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257276.
Повний текст джерелаLi, Shaomeng. "Wavelet Compression for Visualization and Analysis on High Performance Computers." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23905.
Повний текст джерелаCarpenter, John Stuart. "Estimates of Interfacial Properties in Cu/Ni Multilayer Thin Films using Hardness and Internal Stress Data." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1285006915.
Повний текст джерелаSaïghi, Ali. "Comparaison des essais au laboratoire et in situ : exemple du triaxial et du pressiomètre." Châtenay-Malabry, Ecole centrale de Paris, 1998. http://www.theses.fr/1998ECAP0689.
Повний текст джерелаKharaghani, Saeed. "Localisation des grandes déformations au laboratoire et in situ." Châtenay-Malabry, Ecole centrale de Paris, 1994. http://www.theses.fr/1994ECAP0373.
Повний текст джерелаIssa, Inas. "In situ TEM nanocompression and mechanical analysis of ceramic nanoparticles." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI008/document.
Повний текст джерелаIn this study, we propose an innovative mechanical observation protocol of ceramics nanoparticles in the 100nm size range. This Protocol consists of in situ TEM nanocompression tests of isolated nanoparticles. Load–real displacements curves, obtained by Digital Image Correlation, are analyzed and these analyses are correlated with Molecular Dynamics simulations. By this protocol a constitutive law with its mechanical parameters (Young modulus, Yield stress...) of the studied material at the nano-scale can be obtained. In situ TEM nano-compression tests on magnesium oxide nanocubes are performed. Magnesium oxide is a model material and its plasticity is very well known at bulk. The MgO nanocubes show large plastic deformation, more than 50% of plastic strain without any fracture. The TEM results are correlated to MD simulations and the deformation mechanism can be identified.The size effect and the electron beam effect on the yield strength are investigated. In a second part of the dissertation, we present a study on transition alumina nanoparticles compacted in a Diamond Anvil Cell at different uniaxial pressures. Thin Foils of these compacted nanoparticles are prepared by FIB for HRTEM Observations. Their analysis reveals the plastic deformation of the nanoparticles. The crystallographic texture observed inthese compacted nanoparticles in DAC shows a preferred orientation of the {110} lattice planes, orientated perpendicular to the compression direction. This is compatible with the slip system. This argument was reinforced with a preferred orientation of slip bands observed during in situ TEM nano-compression tests. Moreover, electron diffraction patterns (Debye Scherrer) analysis on these compacted transition alumina nanoparticles reveals the decrease of the presence of gamma-alumina and the increase of delta-alumina with increasing pressure. This reveals the phase transformation with increasing pressure from gamma to delta* alumina
Liebaert, Philippe. "Etude de la forgeabilité des aciers à haute température : mise en oeuvre d'essais de criquabilité." Valenciennes, 1991. https://ged.uphf.fr/nuxeo/site/esupversions/91ceec35-dd8b-40dd-85f0-c5e0c2f054ae.
Повний текст джерелаLehmann, Henry [Verfasser], Bernhard [Akademischer Betreuer] Jung, Bernhard [Gutachter] Jung, and Gerik [Gutachter] Scheuermann. "Temporal Lossy In-Situ Compression for Computational Fluid Dynamics Simulations / Henry Lehmann ; Gutachter: Bernhard Jung, Gerik Scheuermann ; Betreuer: Bernhard Jung." Freiberg : Technische Universität Bergakademie Freiberg, 2018. http://d-nb.info/1226100805/34.
Повний текст джерелаGuérin, Jean-Dominique. "Analyse des essais de compression et de traction des aciers après solidification in situ et des essais d'indentation des aciers phosphatés." Valenciennes, 1993. https://ged.uphf.fr/nuxeo/site/esupversions/b769f69b-4777-454d-94ad-c3bac6b6fab1.
Повний текст джерелаDevillard, Julie. "Lien entre microstructure et résistance à la compression du gypse moussé." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI043.
Повний текст джерелаThis study focuses on the microstructural and mechanical characterization of foamed gypsum, the core material of lightweight gypsum boards, with a high (75%) multi-scale porosity. The objective of this work is to determine the influence of the microstructure of foamed gypsum on the hardness measured in spherical indentation and to analyze the damage mechanisms for different microstructures. Spherical indentation tests were conducted on samples showing variations in microstructural features of foamed gypsum. The results of these tests show that density has a first-order influence on hardness and that the dispersion of hardness measurements in spherical indentation can be related to heterogeneity in macroporosity. In situ indentation tests were also carried out, with X-ray tomography and digital volume correlation (DVC) analysis, in order to accurately study the damage mechanisms. Two different modes of damage were determined according to the densities considered (variable macropore fraction). The results of these tests were used to feed an analytical model, based on an energy criterion that links the indentation force to the damaged area under the indenter. This provides the prediction of the indentation force-displacement curve specific to a microstructure with a scan of the initial microstructure as the only input data. Numerical modelling was also carried out using the finite element method with consideration of the actual microstructure, at two scales. The densified areas were properly predicted by different behaviour models based on plasticity criteria
Foscan, Tiziana. "Mechanical characterization of double-wythe masonry walls with a view to in-situ testing methods." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Знайти повний текст джерелаSylvain, Wilgens. "Étude de la plasticité du monocristal de phase MAX par déformation aux petites échelles." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2307/document.
Повний текст джерелаThe thesis's goal is to study the deformation, at microscopic scale, of the MAX phase Ti2AlN synthesized by powder metallurgy. This work is divided into three parts: in the first part, the interest has been put on the hysteretic behavior of the MAX phases via cyclic mechanical solicitations, during spherical indentation tests and ex-situ compression of micro-pillars, on differently orientated grains beforehand determined by EBSD. In the second part, we were interested into the micro-pillar's deformation via insitu cyclic compression tests coupled with Laue micro-diffraction. The goal was to analyse the evolution diffraction lines during the pillar's deformation in order to highlight the elementary deformation mechanisms and to observe the finale structures via the post-mortem SEM imaging of the pillars. Finally, a last part was devoted to study the deformation mechanisms in temperature at microscopic scale via nano-indentation tests up to 800°C. The characterization of the slip lines on the surface has been revealed by AFM and that of t he microstructural configurations (dislocations) under the indent has been done by TEM. All data collected by these various tests at the small scales have refined our understanding of the deformation mechanisms of crystal MAX phase, particularly with respect to the models usually proposed in the literature
Capolo, Laura. "Contribution à l'étude des hétérogénéités de déformation viscoplastique de la glace Ih mono et multi cristalline : essais de compression in-situ sous rayonnement X." Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00175271.
Повний текст джерелаHauss, Grégory. "Microtomographie X de matériaux à comportement pseudo-fragile : Identification du réseau de fissures." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00789670.
Повний текст джерелаWarner, Wyatt Young. "Characterization of Local Void Content in Carbon Fiber Reinforced Plastic Parts Utilizing Observation of In Situ Fluorescent Dye Within Epoxy." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7772.
Повний текст джерелаKhosravani, Ali. "Application of High Resolution Electron Backscatter Diffraction(HR-EBSD) Techniques to Twinning Deformation Mechanism in AZ31 Magnesium Alloy." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3432.
Повний текст джерелаGuitton, Antoine. "Mécanismes de déformation des phases MAX : une approche expérimentale multi-échelle." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2280/document.
Повний текст джерелаIt is commonly believed that plastic deformation mechanisms of MAX phases consistin basal dislocation glide, thus forming pile-ups and walls. The latter can form local disorientationareas, known as kink bands. Nevertheless, the elementary mechanisms and the exact role ofmicrostructural defects are not fully understood yet. This thesis report presents a multi-scale experimentalstudy of deformation mechanisms of the Ti2AlN MAX phase. At the macroscopic scale,two kinds of experiments were performed. In-situ compression tests at room temperature coupledwith neutron diffraction brought new insight into the deformation behavior of the different grainfamilies in the polycrystalline Ti2AlN. Compression tests from the room temperature to 900 °Cunder confining pressure were also performed. At the mesoscopic scale, deformed surface microstructureswere observed by SEM and AFM. These observations associated with nanoindentationtests showed that grain shape and orientation relative to the stress direction control formationof intra- and inter- granular strains and plasticity localization. Finally, at the microscopic scale,a detailed dislocation study of samples deformed under confining pressure revealed the presenceof dislocation configurations never observed before in MAX phases, such as dislocation reactions,dislocation dipoles and out-of-basal plane dislocations. In the light of these new results, mechanicalproperties of MAX phases are discussed
Pour, Shahid Saeed Abadi Parisa. "Mechanical behavior of carbon nanotube forests under compressive loading." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47699.
Повний текст джерелаLahouij, Imène. "Mécanismes de lubrification des nanoparticules à structure Fullerène : approche multi-échelle." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00790813.
Повний текст джерелаGhazi, Arash. "Microstructural computational modeling of the mechanical behaviour of closed-cell foams: from tessellation-based to CT scan-based modeling." Doctoral thesis, Universite Libre de Bruxelles, 2020. https://dipot.ulb.ac.be/dspace/bitstream/2013/306841/3/Thesis.pdf.
Повний текст джерелаDoctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
Soler, Maxime. "Réduction et comparaison de structures d'intérêt dans des jeux de données massifs par analyse topologique." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS364.
Повний текст джерелаIn this thesis, we propose different methods, based on topological data analysis, in order to address modern problematics concerning the increasing difficulty in the analysis of scientific data. In the case of scalar data defined on geometrical domains, extracting meaningful knowledge from static data, then time-varying data, then ensembles of time-varying data proves increasingly challenging. Our approaches for the reduction and analysis of such data are based on the idea of defining structures of interest in scalar fields as topological features. In a first effort to address data volume growth, we propose a new lossy compression scheme which offers strong topological guarantees, allowing topological features to be preserved throughout compression. The approach is shown to yield high compression factors in practice. Extensions are proposed to offer additional control over the geometrical error. We then target time-varying data by designing a new method for tracking topological features over time, based on topological metrics. We extend the metrics in order to overcome robustness and performance limitations. We propose a new efficient way to compute them, gaining orders of magnitude speedups over state-of-the-art approaches. Finally, we apply and adapt our methods to ensemble data related to reservoir simulation, for modeling viscous fingering in porous media. We show how to capture viscous fingers with topological features, adapt topological metrics for capturing discrepancies between simulation runs and a ground truth, evaluate the proposed metrics with feedback from experts, then implement an in-situ ranking framework for rating the fidelity of simulation runs
Lamb, Juliano Rodrigo. "Sistema de informação para ajuste dos dados de tensão-deformação nos ensaios de compactação do solo." Universidade Estadual do Oeste do Parana, 2006. http://tede.unioeste.br:8080/tede/handle/tede/181.
Повний текст джерелаThe soil compaction is a harmful phenomenon to the agricultural sector, intensified with the current model of culture adoption though the use of machines weighed in the culture systems, where these can exert superior pressures to the soil load support capacity. With the soil compaction and compression there is a reduction of the void ratios face to the air and water expulsion, that composes the system, harming the water absorption and minerals for the plants roots, as well as increasing the resistance of the ground to the penetration. By the way, it is formed becomes important the accomplishment of trials of compression for determination of the compaction levels, either in field through assays in situ or laboratory trials. The difficulty presented in trials of this nature, this related with the analysis of the gotten data and with the determination of the compression curves and stress point. Face this conjuncture one utilized the systems of information with the development of application of data base for the adjustment of the data of tension-deformation in trials in situ and laboratory. The system was developed using the environment of development Borland© Delphi© with data base Firebird and methodologies Oriented Objects and to 3Tier. With data proceeding from carried through trials, the software have demonstrated to efficiency in the reading and filtering of in situ trials data, security in the storage of all the referring data to the trials, as well as agility and precision in the determination of the curves of compression of the ground and in the esteem of the stress point. The results still allow concluding that, the traffic of machines in the activities in field intensify the phenomenon of the compaction, and that sinkage plate and oedometer are important in the accomplishment of trials of soil compression.
A compactação do solo é um fenômeno danoso ao setor agrícola, intensificado com a adoção do modelo de produção atual que utiliza nos sistemas de cultivo. máquinas pesadas que podem exercer pressões superiores à capacidade de suporte do solo. Com a compactação e compressão do solo ocorre uma redução do índice de vazios, face à expulsão do ar e da água que compõem o sistema, prejudicando a absorção de água e minerais pelas raízes das plantas e aumentando a resistência do solo à penetração. Dessa forma, torna-se importante a realização de ensaios de compressão para determinação dos índices de compactação, seja em campo por meio de ensaios in situ ou em ensaios laboratoriais. A dificuldade apresentada em ensaios desta natureza, está relacionada à análise dos dados obtidos e com a determinação das curvas de compressão e índice de pré-consolidação. Face a essa conjuntura procurou-se a utilização de sistemas de informação com o desenvolvimento de um aplicativo de banco de dados para o ajuste dos dados de tensão-deformação em ensaios in situ e em laboratório. O sistema foi desenvolvido usando o ambiente de desenvolvimento Borland© Delphi© com banco de dados Firebird e metodologias Orientada a Objetos e 3Tier. Alimentado com dados provenientes de ensaios realizados, o software demonstrou eficiência na leitura e filtragem dos dados de ensaios in situ, segurança no armazenamento de todos os dados referentes aos ensaios, bem como agilidade e precisão na determinação das curvas de compressão do solo e na estimação do ponto de pré-consolidação. Os resultados ainda permitem concluir que o tráfego de máquinas, nas atividades em campo, intensifica o fenômeno da compactação e que o penetrômetro e o oedômetro são importantes na realização de ensaios de compressão do solo.
RATHOD, CHANDRASEN. "DIFFRACTION STUDIES OF DEFORMATION IN SHAPE MEMORY ALLOYS AND SELECTED ENGINEERING COMPONENTS." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2892.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering
MAYEUR, BERTRAND. "Mesure et modelisation des contraintes naturelles dans un massif rocheux alpin : effets de la topographie, de l'anisotropie et des contraintes tectoniques ; application au projet de tunnel maurienne-ambin." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10198.
Повний текст джерелаLIN, KAI-PENG, and 林凱鵬. "Mechanical Properties of Micropillars Using In Situ Transmission Electron Microscope Compression And Indentation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/65z5pu.
Повний текст джерела國立高雄應用科技大學
機械工程系
106
In this study, the mechanical properties of micropillars were analyzed by in situ transmission electron microscopy compression and indentation. The results show that the stress wave propagation and structural variations of the material can be found during in situ compression. After compression process, because of the internal structure of the material defects and damage, the micropillar will be bended and broken. The Young's modulus of NaCl, Al2O3, NiAl and NiTi alloy micropillaby in situ compression test were 10.4-23.9 GPa, 25.5-347.5 GPa, 32.7-44.9 GPa and 5.9-24.4 GPa, respectively. Vickers hardness values of NaCl, Al2O3, Cu, NiAl and NiTi alloy were found to be 196-260 MPa, 14.0-20.2 GPa, 1.1-1.2 GPa, 2.9-4.5 GPa and 7.4-7.7GPa, respectively. In the study, it was found that the phenomenon of dislocation and dislocation loop appeared in the internal structure of the Al2O3 by high-resolution transmission electron microscopy after the Vickers hardness test. The mechanical behavior and deformation mechanism of Cu micropillar structures through molecular dynamics simulation after compressed were also investigated in this study. As can be seen from the research results, Cu pillars have dislocation and stress wave transmission phenomenon during the compression process, and the diameter of the Cu pillar has increased with the increase of the compression displacement. Finally, through theoretical exploration and simulation analysis, the mechanical properties of micropillar should establish the important properties and the mechanism of structures and theory.
Wu, Jui-Yang, and 吳瑞洋. "Mechanical Behaviors of Cu6Sn5 in 3D IC Micro JointsUsing Micropillar Compression." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/hvvnmy.
Повний текст джерела國立臺灣大學
材料科學與工程學研究所
107
As semiconductor industry is confronted with the challenge of physical limit in scaling down transistor size, three dimensional integrated circuits (3D ICs) serve as one of the most promising technologies to extend Moore’s law (More-Moore) or even go More-than-Moore. Yet, the miniaturization of micro solder joints, an essential joining structure in 3D IC technology, leads to quick transformation from solders into intermetallic compounds (IMCs) in the joint. When a large portion of micro joints is occupied by IMCs, the mechanical properties and deformation behaviors of micro joints are no longer dominated by solder as in conventional flip-chip joints and ball grid array (BGA) joints, and instead intermetallics are anticipated to shoulder primary responsibility of mechanical reliability of micro joints. In light of this, this study puts emphasis on mechanical reliability assessment of single crystalline IMCs and IMC-based multiphase structures by means of nanoindentation and micropillar compression. In order to eliminate the influence of indenter, substrate, misalignment and gravity effect under tilt condition, a calibration approach for micropillar compression is firstly established such that Young’s moduli measured from micropillar compression tests are in good agreement with those from nanoindentation. Also, the stress-strain curves show that Cu6Sn5 exhibited one or more strain bursts prior to brittle fracture, and the post-mortem transmission electron microscopy (TEM) analysis suggests that dislocation gliding inside micropillars is involved in strain jumps. Besides, a statistical analysis of the anisotropy in hexagonal Cu6Sn5 is also carried out based on micro-compression as well as nanoindentation results, where Cu6Sn5 exhibits a higher value of Young’s modulus when the loading direction is closer to c-axis. Furthermore, Ni addition into Cu6Sn5 can notably enhance mechanical strength and stabilize the hexagonal structure. Last but not least, multilayered micropillars (Cu6Sn5/Sn/Cu6Sn5 and Cu6Sn5/Cu3Sn/Cu) containing heterogeneous phase interfaces provide insight into overall deformation behaviors in real Cu-Sn interconnects. On one hand, Cu6Sn5/Sn/Cu6Sn5 cylinders exhibit remarkable plasticity in the manner of interface sliding at around 100 MPa, accommodating at least 10% strain and retaining its integrity without any void formation at the interface. On the other hand, multilayered Cu6Sn5/Cu3Sn/Cu micropillars undergo plastic deformation through slip deformation at Cu substrate, suggesting sufficient strength of intermetallic compounds and the interfaces. These results are beneficial in evaluation of validity and reliability of 3D IC micro-joints for chip-stacking applications.
Jia-ShiunChen and 陳家勛. "Simulation by the finite element method for the compression of bulk metallic glass micropillar." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/63053818792571702611.
Повний текст джерелаChou, Hung-Sheng, and 周鴻昇. "Strengthening and Toughening of Zr-Based Thin Film Metallic Glasses and Composites under Nanoindentation and Micropillar Compression." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/14392610155375909609.
Повний текст джерела國立中山大學
材料與光電科學學系研究所
99
Since the first discovery of amorphous alloys in 1960, researchers have explored many unique mechanical, magnetic, and optical characteristics of such materials for potential applications. Up to now, well-developed processes, such as rapid quenching, sputtering, evaporation, pulse laser deposition, etc, have been applied for different applications in micro-electro-mechanical systems (MEMS). Due to the lack of ordered structure, amorphous alloys can bear a high stress in the elastic region. Their plastic deformation stability is also of interest and has been widely studied. The shear-band characteristic, a kind of inhomogeneous deformation mechanism, dominates the deformation after yielding at room temperature. While a shear band nucleate, its propagation usually cannot be arrested or stopped. In other words, the occurrence of matured shear bands needs to be prevented. There are two major approaches in this aspect. The first is to increase the material yield strength so as to delay the shear band nucleation. Another is to incorporate intrinsic or extrinsic particles so as to absorb the kinetic energy of shear bands in the amorphous matrix. In this study, we utilize three strategies to control the propagation of shear bands in thin film metallic glasses (TFMGs): sub-Tg annealing, the addition of strong element in solute form, and the introduction of strong nanocrystalline layers. For sub-Tg annealing, the base alloy system is Zr69Cu31, with a base film hardness of 5.1 GPa measured by nanoindentation. After annealing, the hardness exhibits ~30% increase. Without the occurrence of the phase transformation, as confirmed by X-ray diffraction, the possible reaction during sub-Tg annealing is attributed to structural relaxation, not crystallization. The full width at half maximum of the X-ray peak exhibits a decreasing trend in the using X-ray and transmission electron microscopy diffraction, meaning the excess free volumes forming during vapor-to-solid deposition process would be annihilated by localized atomic re-arrangement. Moreover, the formation of medium-ordering-range clusters was confirmed utilizing high-resolution transmission electronic microscopy. The denser amorphous structure leads to the increment of hardness. For the addition of Ta in Zr55Cu31Ti14, sputtering provides a wide glass forming range with solubility of Ta approaching ~75 at%. With increasing Ta content, the elastic modulus and hardness increase slowly. A steep rise occurs at ~50 at% of Ta. Up to 75 at% of Ta, the elastic modulus and hardness approaches 140 GPa and 10.0 GPa, respectively (100% increment). Up to now, Ta-rich TFMGs exhibit the highest elastic modulus and hardness among all amorphous alloys fabricated using vapor deposition techniques. The irregular increase is attributed to the formation of Ta-Ta bonding. A large quantity of Ta bonds would lead to the formation of Ta-rich nanoclusters, drastically decreasing the strain rate while shear band propagates under nanoindentation and microcompression tests. The introduction of nanocrystalline Ta layers can not only effectively enhance the yield strength but also serve as the absorber for the kinetic energy of shear bands, revealing ductility in the microcompression test.
Lehmann, Henry. "Temporal Lossy In-Situ Compression for Computational Fluid Dynamics Simulations." Doctoral thesis, 2017. https://tubaf.qucosa.de/id/qucosa%3A31413.
Повний текст джерела(6635129), Kayla Haruko Yano. "In Situ TEM Mechanical Testing of Irradiated Oxide Dispersion Strengthened Alloys." Thesis, 2019.
Знайти повний текст джерела(7036280), Cuncai Fan. "Radiation Response of Nanostructured Cu." Thesis, 2019.
Знайти повний текст джерелаChun-WeiTang and 湯君偉. "Effects of Diabetes Mellitus on Mechanical Behavior of Peripheral Nerve Tissues and Vasa Nervora under In Situ Circular Compression." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/03082780865605227003.
Повний текст джерела國立成功大學
機械工程學系
104
Ischemia of vasa nervora in peripheral nerves may be the main cause of diabetic neuropathies. Diabetic neuropathies are also related to clinical morbidity of carpal tunnel syndrome. Thus, from biomechanics perspective, study of mechanical behavior of peripheral nerve tissues and vasa nervora under compression and diabetic circumstances may help understanding mechanisms of retarded blood flow in nerve. In this study, in situ compress-and-hold experiments were implemented by circular compression on sciatic nerve of rats and blood flow within vasa nervorum was observed by using Doppler optical coherence tomography (D-OCT) simultaneously. Mechanical property of nerves was determined by fitting the data from the experiments with a quasi-linear viscoelasticity (QLV) model. Cross sectional area and morphology of vasa nervorum and their variations with time were estimated from D-OCT image data using new methods. The finite element method (FEM) was utilized to simulate stress distribution and morphology changes of substructures in the nerve. Results of this study suggested diabetic nerves are more viscous in mechanical property and their vasa nervora are more vulnerable to circular compression. Results from FEM suggested that the perineurium could sustain more stress while the epineurium served as cushion under circular compression. The results also indicated there are specific regions in epineurium which sustained less stress and blood vessels in such regions had less tendency to collapse. The large blood vessels in nerve are most likely to be settled on these regions according to tissue slices. Comparison between D-OCT data and FEM results suggested that vasa nervora have auto-regulation ability.
EricChia and 謝博弈. "In situ Circular Compression and Doppler Optical Coherence Tomography Studies on Effects of Diabetic Mellitus on Vesa Nervonum of Sciatic Nerve." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/45862378173555611749.
Повний текст джерела國立成功大學
機械工程學系
102
Diabetes mellitus is one of the most common diseases in the world and can cause many types of neuropathies, and even mortality. It is therefore important to understand how diabetes mellitus alters the mechanical properties of nerve tissues and their blood vessels. This study is to examine the dilatation of vasa nervorum inside the nerve trunk by using circular compression test and Doppler OCT, then proposes a biomechanical model to explain how vasa nervorum interact with the compression force and compare the simulated results with images captured by Doppler OCT. In this study, in situ compression-and-hold circular compression tests were applied to the sciatic nerves of both diabetic rats and normal rats. Doppler optical coherence tomography (Doppler OCT) was then utilized to monitor the configuration of the vasa nervorum in two groups of rats. The force data acquired in the compression tests were fitted by using Fung’s quasi-linear viscoelastic model (QLV) to determine the viscoelasticity of the nerves. The results show that the nerves in the diabetic group had a longer relaxation time but lower stress responses than those in the normal group. Consequently, the Doppler OCT observations reveal that in contrast to the normal vasa nervorum, the diabetic vasa nervorum did not dilate in the relaxation phase. This study also provides that the biomechanical properties of vasa nervorum may be described as shell model and confirms the autoregulatory responses of blood vessels. In summary, the diabetic nerve is friable and its vasa nerverom is fragile and may explain why the diabetic patients are more prone to carpal tunnel syndrome.
"Deformation Behavior of adidas BOOST(TM) Foams Using In Situ X-ray Tomography and Correlative Microscopy." Doctoral diss., 2020. http://hdl.handle.net/2286/R.I.62793.
Повний текст джерелаDissertation/Thesis
Doctoral Dissertation Materials Science and Engineering 2020
Grave, Douglas Marcus Hadley. "Determination of the factors affecting the performance of grout packs." Thesis, 2007. http://hdl.handle.net/10539/2138.
Повний текст джерелаIn tabular mining, common in South African gold and platinum mines, the removal of the tabular ore body by mining operations leaves behind excavations known as stopes. These stopes form the production areas of a mine and have to be supported in order that a safe working environment is created. Stopes generally have widths of close to a metre but, in some areas and on certain reefs, may be much wider. Prior to the 1980s, a combination of in-stope pillars and timber was used to support these stopes, but innovations from the 1970s have produced grout packs as a viable support option. These packs are cast in situ through the use of cemented classified tailings gravitated from surface and placed in reinforced geotextile bags at the stope face. As these packs cure and become rigid they are able to bear load when compressed by stope closure. In this way, the packs keep the working areas open. To quantify the load-bearing capacity of grout packs, a range of sizes and designs was tested in a laboratory press and, thereafter, a select few were tested underground. Initially, two aspects of grout packs that had not been adequately quantified previously were addressed. These were: the in situ load / compression characteristics of different forms of grout packs; and the relationship between laboratory test results and in situ performance. The laboratory test programme was extended to allow for an investigation into methods of improving the yieldability of grout packs and the possibility of using them to replace in-stope pillars. It was found that the factors that most affect the initial strength and post-failure characteristics of a grout pack are: the grout strength; the amount and type of steel reinforcement; the inclusion of ancillary columnar support; and the height and diameter of the pack. It was also found that grout packs could be used to replace in-stope pillars, but that pack strength and spacing should be conservatively calculated before implementation. A provisional relationship between the behaviour of packs tested in a press and those placed underground was determined.
Englmaierová, Martina. "Mechanické vlastnosti zemin z pískovny Kolný v třeboňské pánvi." Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-295820.
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